Prevention of leakage of make gas from stack valve of a combustible gas generating set



Feb. 12, 1952 v T. B. WILLIAMS 7 2,535,417

PREVENTION OF LEAKAGE OF MAKE GAS FROM STACK VALVE OF A COMBUSTIBLE GAS GENERATING SET 4 Filed April 15, 1948 2 Fig.1. 25' 2O 8 24 2i il\ 15 X I! 1 41 7 Q7 z 43 42 Q2 40 5.6 50 51 36 59 38 '57 V n J INVENTOR lkomaslimoishillms ATTORNEY Patented Feb. 12, 1952 PREVENTION OF 2,585,417 LEAKAGE 0F MAKE GAS FROM STACK VALVE OF A COMBUSTIBLE GAS GENERATING SET Thomas Brooks Williams, Taunton, Mass., as-

signor to Allied Chemical & Dye Corporation, New York, N. Y., a corporation of New York Application April 13, 1948, Serial No. 20,776

This invention relates to apparatus for producing combustible gas, such as blue gas, carbureted water gas and oil gas.

Equipment heretofore used for the manufacture of carbureted water gas involved a generator containing a bed of fuel, a carburetor, superheater and stack connected in series, the stack being provided with a gas off-take independent of the stack opening through which the blast gases are discharged into the atmosphere. The 01ftake is employed for flow of make gas from the stack to a washbox or other by-produc't recovery apparatus during the gas making period of operation; the stack opening during this period of operation is closed by the stack valve. In the manufacture of blue gas and oil gas similar equipment is often used, or the generator may communicate with an igniter in which the blast gases are ignited and burned, the resulting products of combustion from the igniter flowing through a stack and thence through the stack valve opening into the atmosphere, the stack valve being open for this purpose. During a succeeding step in the process, the blue gas formed by passage of steam through the fuel bed in the generator or the oil gas produced by cracking of oil in the generator flows through the igniter and stack and thence through the gas off-take leading from the stack to a washbox, the stack valve being closed.

In the operation of such equipment it has been found that during the make when the stack valve is closed and the make gas flows through the stack into the gas off-take leading therefrom, invariably leakage of gas takes place through the closed stack valve due, for example, to improper seating of the stack valve caused by warping of the seat of the valve or by the deposit of carbon and other material on the seat. The amount of such leakage represents a very substantial loss of make gas.

It is an object of this invention to provide a stack valve which eliminates leakage of make gas therethrough when the stack valve is closed.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

In accordance with this invention the stack valve is provided with a steam curtain around the inner periphery of the seating surface, so, that when closed a body of steam is maintained in the vicinity of the closed valve under a pressure sufiicient to prevent escape or leakage of make gas through the closed stack valve, leakage, if any, taking place being of steam rather than the make gas. This steam curtain tends to remove carbon and other deposits from the seating surfaces of 1 Claim. (Cl. 48 -87) 4 seating surface clean and insuring the stack valve, as Well as preventing deposition of carbon onthe seating surface by excluding make gas containing hydrocarbon from contacting the seating surface, thus maintaining the of the valve when in closed position. 7

In the preferred embodiment illustrated on the drawing the invention is shown incorporated in a stack valve for a carbureted water gas set of the reverse flow type, and the description which follows will be confined to this illustrated embodiment of the invention. It will be understood, however, that the novel features and improvements are susceptible to other applications, such,

for example, as blue-gas or oil gas equipment containing, say a generator, igniter and stack, or just a generator and stack when it is desired not to burn the blast gases, the stack being provided with an ofE -take communicatmg with the washbox or other by-product recovery apparatus. Hence, the scope of this invention is not confined to the embodiment herein described.

In the accompanying drawing forming a part" of this specification and showing'for purposes of exemplification preferred forms of this invention without limiting the claimed invention to such illustrative instances,

Figure 1 is a diagrammatic side elevational view H of a reverse flow water gas set, the stack of which giYiS equipped with a stack valve embodying this invention;

Figure 2 is a vertical section on a greatly enlarged scale as compared with the scale of Figure 1, showing a stack valve embodying this invention; and

Figure 3 is a vertical section on substantially the same scale as Figure 2 showing a modified form of' stack valve embodying this invention.

V In Figure" 1 is shown a water gas set compris- **ing a generator I0, carburetor i I and superheater l2. The carburetor is elevated and its base is connected with the top of generator It by a passageway I3. Generator I0 is equipped with W the usual grate (not shown)" for supporting a, bed

proper seatingleading into the top of the superheater l2. Gas outlet 20 at the base of superheater |2 leads into a vertical refractory lined stack 2| provided at its top with a stack valve 22 hereinafter more fully described. The stack 2|, preferably is of a height somewhat greater than the height of the superheater I2, so that, as shown in the drawing, stack valve 22 is disposed above the top of the superheater and constitutes the highest point of the set. Hence, when stack valve 22 is open during the blasting cycle, stack 2| provides the necessary draft for insuring flow from the set into the atmosphere of the products of combustion generated in carburetor H and superheater |2 by burning the blast gases produced in generator ID.

A conduit 23 leads from the top of stack 2|, just below stack valve 22, into a valve casing 24 which in turn communicates by a pipe 25 with a washbox 26. Backrun line 21 leads from the base of the generator beneath the grate into the valve casing 24. Valve casing 24, as well known in this art, is provided with a three-way valve for reversing fiow through the set, i. e., in one position it permits flow of uprun gas from the superheater through stack 2|, conduit 23, valve casing 24, pipe 25 into washbox 26, while closing the backrun line 21, and when reversed, i. e., moved to its other operative position, it opens backrun line 21 so as to permit flow of backrun gas therethrough into the washbox 26 while closing conduit 23 leading into casing 24. A gas ofi-take 28 leads from the washbox to the usual purification equipment. Backrun steam inlet 29 is provided for supplying steam to the top of the stack, which, as above indicated, communicates with the base of the superheater. A suitable steaminlet (not shown) is provided for supplying steam to the base of the generator for flow up through the fuel bed therein. The various valves of the set may be operated manually or automatically in any desired manner to carry out the steps of the water gas cycle, e. g., the valves may be operated by hydraulic cylinders controlled from a control nest, as well known in this art.

In accordance with this invention stack valve 22 comprises a seat 30, preferably in the form of a suitable casting, bolted as at 3|, to the top of the stack 2|. Stack lid 32 desirably in the form of a dished casting has its periphery 33 formed to seat on the seat 39 and provide a substantially gas tight closure for the stack. Lid 32 is carried by an arm 34 pivoted at 35 to a suitable bearing support 36 carried by seat 39. Arm 34 may be operated by any suitable mechanism to open or close lid 32. A plate 31 is secured to the underside of lid 32, for example, by being welded or otherwise fastened to ribs 38, cast on the inside of lid 32. Plate 31 is circular in shape and has a diameter somewhat less than the inside diameter of the inner peripheral edge of lid 32 providing a clearance 39 between the peripheral edge of circular plate In the modification of Figure 3, seat 33 is prov vided with an integral annular channel 44 defined by an outer annular wall 45, the upper edge of which provides a seat for lid 32, and an inner annular wall 46, the upper edge 41 of which extends inwardly towards wall 45 producing an annular opening 48. A steam pipe 49 leads into the annular channel 44 to supply steam thereto, the steam escaping through the opening 43 where it builds up a body of steam under pressure in the neighborhood of the closed valve. In the modification of Figure 3 it is not necessary to use a steam pipe having a flexible portion for supplying steam to the stack valve,

as is the case in the modification of Figure 2 in which the steam is supplied to the stack lid which must be open during the blasting cycle and closed during the make cycle.

In operation of the set hereinabove disclosed, air is passed through the fuel bed in generator ID, the air being introduced through inlet l1 and passed up through the fuel bed. Secondary air may be admitted through I6 to support the combustion of the blast gases thus generated which flow through |3 up through carburetor burning therein, the burning blast gases flowing down through superheater l2, up through stack 2|, exiting into the atmosphere, stack valve 22 being open.

After this blasting step the stack valve 22 is closed and the valve in valve casing 24 positioned to close backrun line 21 and permit flow through line 23 into casing 24. Steam is admitted into the bottom of the generator, passes up through the fuel bed therein, the resultant Water gas flowing up through the carburetor H where it may be carbureted, if desired, and the carbureted water gas passed down through the superheater I2, up through stack 2| into conduit 23, valve casing 24, conduit 25 into washbox 26. Simultaneously, steam is admitted to the stack valve forming a body of steam in the upper portion of the stack valve at a pressure somewhat greater than the pressure of the make gas passing through the stack into the gas offtake 23 during the uprun period. This body of steam prevents escape of gas through the stack valve 22, should it be imperfectly seated for any reason. Steam which escapes through the closed stack valve exits into the atmosphere where it does no harm. The small amount of steam flowing with the make gas through conduit 23 simply adds to the moisture content of the gas and is removed along with the moisture normally carried by the gas in the usual purification treatment.

. The uprun may be followed by a backrun during which steam is introduced into the stack through steam inlet 29, is preheated as it flows through the stack, superheater and carburetor, passes down through the fuel bed, the resultant water gas being withdrawn from the base of the generator through backrun pipe 21 and passed through valve housing 24 and conduit 25 into the washbox 26. During this backrun step of the process there is no need to introduce steam to the stack valve 22.

It will be noted this invention provides a body of steam near the inner periphery of the seating surface of the stack valve, so that when the valve is closed during the portion of the gas making cycle when make gas is passing through the stack, the steam prevents leakage of make gas through the valve with consequent saving of the make gas. Further, the steam exerts a cleaning action to remove carbon and other deposits from the seating surfaces of the stack valve, as well as prevents formation of carbon deposits by excluding from contact with the seating surfaces gases containing hydrocarbons which would otherwise be leaking through the stack valve. Moreover, the steam cools the stack valve and lid after each blasting step when the valve is subjected to the high temperature blast gases and before these parts of the stack valve are again subjected to the high temperature blast gases, thereby maintaining the stack valve and lid at a substantially lower temperature and preventing Warping of these parts.

Since certain changes in the gas making equipment, which embodies the invention, may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

A stack valve for a stack provided with a gas oiT-take and a stack opening independent of said gas oil-take, a seating surface surrounding said stack opening, a stack valve lid in the shape of a, dished member having a peripheral edge 6 for seating on said seating surface, a plate on the under side of said lid secured thereto and having its peripheral edge spaced from the inner peripheral edge of said lid to provide an annular clearance between saidedges, and an inlet for supplying steam to the inside of said lid for flow through said annular clearance when said stack valve lid is seated on said seating surface.

THOMAS BROOKS WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,001,028 Henderson Aug. 22, 1911 1,587,972 McIntosh et a1 June 8, 1926 1,724,982 Trumble Aug. 20, 1929 2,133,479 Schmalfeldt Oct. 18, 1938 2,218,266 Pearson Oct. 15, 1940 2,489,925 Omwake Nov. 29, 1949 

